The process of producing high purity copper involves several stages, starting with the receiving and sampling of copper concentrates. It is important to perform a sampling thereof and classify them according to the copper, iron, silica concentration as well as impurities such as mainly arsenic, antimony and zinc.
Subsequent to the classification, the concentrate enters the drying stage where the humidity is reduced from 8% to 0.2% then the dried concentrate enters the smelting process whose objective is achieving the change of state which allows that the concentrate passes from a solid state to a liquid state in order for the copper to be separated from the other elements that are part of the concentrate.
The copper concentrate fusion is the result of the instantaneous self-ignition thereof which takes place at high temperatures (greater to 1200° C.). In this process the concentrate passes from the solid state to the liquid state. The elements that are part of the ores that are present in the concentrate are separated according to its weight leaving the lightest ones on the upper part of the molten metal which is referred to as scrap which are mainly iron and silica rich-phases, while the copper associated to the sulphur which is heavier, is concentrated in the lower part of the reactor which is called white metal or matte.
In this way, it is possible to separate both parts by removing them from the reactor by means of bleed-of passages located at different levels.
The fusion furnaces or reactors must be constantly loaded and need permanently to be bled off. The rich-copper material is conveyed in liquid form through pots or chutes to the conversion process where a copper-rich phase is produced which is called blister copper (98.5%), this product is subsequently taken in liquid form through pans or channels to a refining process where the main impurities such as dissolved sulphur, dissolved oxygen, and impurities such as arsenic, antimony, bismuth, lead and others are eliminated, in a way that the product finally obtained is anode copper with an overage purity of 99.5% of copper.
The anode copper is molded and solidified with a rectangular geometry, forming an anode plate (1) with lugs (2) as shown in FIG. 1.
The most used shape to mold an anode copper is by means of a casting wheel which has a determined quantity of copper molds wherein the copper is poured at a temperature lower or equal to 1200° C., once the cooper is cast into the casting wheel, this starts rotating and the molten copper begins to cool off in a first stage at an ambient temperature until the upper part of the copper is solid. Subsequently, the copper passes through a cooling section which has an upper and lower water cooling portions and in this section the copper reduces its temperature until being in a complete solid state to be taken to the electrolytic refining plant so as to produce a high-purity cathode having concentrations higher or equal to 99.9% in copper.
The anode copper is formed by a mold (7) which has a central cavity (8) of rectangular shape to receive the liquid copper which forms the anode plate (1). In the upper part of said mold (7), and towards the corners of the central cavity (8) are located two cavities (9) to receive the liquid copper which forms the lugs (2) as shown in FIGS. 6 and 7.
In refineries, the anode (1) is introduced in an electrolytic cell (3) which has a cathode (4) and can be a permanent cathode or mother sheet depending on the technology to be used, together with its hanging bar (5). The electrolytic cell (3) is filled with an acid solution and electricity is applied to the contacts (6) in order to produce the copper electroplating from the anode (1) to the cathode (4) as shown in FIGS. 2 to 5. In this process, the anode (1) is only submerged up to the continuous zone of the lugs (2), therefore, the upper part of the anode (1) does not participate in the electrolysis as shown in more detail in FIG. 3, using the lugs (2) only for the transport thereof and for the electrical contact.
At the end of the electrolytic cycle, this part of the anode remains intact and it becomes an important part of the rest of the anode, together with the undissolved material, which is called scrap. This material has to be smelted again in order to form a new anode (1) and to continue the complete cycle. This product is formed in all the existing refineries and the processing cost is high and said processing is performed by means of different existing technologies available in the market.
The present invention proposes a new geometric shape of the anode (1) which can separate the lugs (2) from the body of the anode, by keeping a rectangular configuration or another shape with the dimensions requested by the electro-refining technology to be used. Subsequently, and downstream of the molding process, a fastening system must be incorporated which is already factory-dimensioned and standardized according to the geometrical dimensions used by the existing electro-refining technologies.
The fastening system can consist of materials resistant to the acid solution used in the electro-erosion and will have conductors which will allow transmitting the electric current to the modified anode in a such a way that the electric contact is appropriate for the electrolysis process.
Several attempts have been made in the state of the art in order to generate bars with lugs for hanging cathodes and anodes in different process within the obtaining of non-ferrous metals.
Thus, for instance, document EP 0284128 published on Sep. 28, 1988 discloses a suspension bar for an anode or cathode sheet in electrolytic refining of metals wherein the core of the suspension bar consists of a material which exhibits a high resistance to bending and a high mechanical resistance, and is surrounded by a sheath of a material with good electrical conducting properties.
This material with good electrical conduction properties is for example copper, wherein near at least one of the ends of the suspension bar, and preferably near both ends, over a length of a least 3 cm and at most 5 cm, the sheath is continuous to the end of said core part. Also, this document discloses a method for manufacturing a suspension bar in which a sheath of copper is formed over a core of steel, starting from a copper tube.
The copper and steel cores are introduced into a copper tube, wherein subsequently the sheath is drawn, with further cores being added, to a total length which essentially corresponds to the change in length of the copper tube occurring as a result of the drawing and, finally, the rod produced is sawn up into the desired length at the points where the copper cores are located. Towards the center, the bar has two hooks to suspend an anode or cathode as the case may be.
Document ES 8303548 (Prengaman et al) discloses a method for the manufacture of a lead anode for the electrolytic extraction of metals.
The lead anode is used in the electrolytic extraction of metals and comprises a sheet of lead anode material provided with one or more recesses on the surface of a lead-tin alloy coated copper bus bar in the slot of which is placed a sheet of lead anode material of one solder that joins the mentioned sheet to the bus bar and of deposits of lead alloy which join the existing joints between the mentioned sheet and the cited bus bar. The solder comprises a lead-tin-silver alloy to be applied in the electrowinning of copper, nickel and zinc.
Document CA 1095841 (Huppi) published on Feb. 17, 1981 discloses an electrode hanger of unitary construction for an electrostatic precipitator having means on the upper end thereof for engaging with a current carrying support means and means on the lower end thereof for receiving an electrode thereon.
Document WO 2000/39366 (Prengaman) published on Jul. 6, 2000 discloses a method of manufacturing an electrowinning anode comprising: adjusting a sheet of lead alloy in a slot in a bus bar; b) holding the bus bar on the sheet; c) electrowining a lead coating on a bus bar; the pin and joint to form a metallurgical bond around the bus bar, pin and joint between the sheet and the bus bar.
None of the documents aforementioned discloses a system proposing a new geometrical shape of the anode with independent fasting means which make possible using said anode without lugs thereby reducing the production of scrap, allowing an enhancement of the process between the smelting and the electro refining.
On the other hand, document WO 2013/038352 A1, property of the same applicants, discloses a system comprising an anode hanger means and an enhanced geometry anode which makes possible to reuse said anode hanger means minimizing the production of scrap, allowing an enhancement of the process between the smelting and the electro-refining wherein said hanger means is formed by a reusable solid central bar to be located on the upper edge of the enhanced geometry anode wherein said reusable solid central bar has on its ends reusable ears having engagement means which take the enhanced geometry anode on its upper corners wherein in the upper corners of said enhanced geometry anode emerge two small upper projections wherein said hanger means comprises a reusable independent central bar wherein on the ends of said reusable independent central bar are fitted two reusable independent ears which have fastening means formed by a lower notch on which the upper projection of the enhanced geometry anode is housed.
This anode and hanger bar system disclosed in document WO 2013/038352 A1 is formed by a solid central bar which must be juxtaposed on the upper edge of the anode so as the independent ears are slid into a female slot and a male rim to form a tongue and groove joint member that makes possible as a rail the joint between the reusable independent central bar and said reusable independent ears. The reusable independent ears are displaced by said rail from the ends of the reusable independent central bar until said reusable independent ears are fitted into the upper small projections on the anode, thereby generating the closure of the system and securing the anode to the hanger means.
The mounting system between the hanging bar and the enhanced geometry anode results quite complex for the operations performed in the plant.
After the anode has been removed from the mold, this must be transported to the mounting zone of the hanging bar. The reusable independent central bar must be juxtaposed and contacted with the upper edge of the anode so as the independent ears are slid on said reusable independent central bar until being fitted with the small projections of the anode and thus closing the system in such a way that the anode and the hanging bar are transported towards the electro-refining process.
Due to the aforementioned, a first object of the present invention is providing a hanging means formed by an independent hanging bar and pivotable lugs connected to each other in such a way the anode mountings results easy.
A second object of the present invention is providing a design of anode which allows it to be resistant to the conveying process between the smelting and refining process in such a way it has a uniform thickness and volume which enhance the benefits of molding and cooling thereby avoiding twists. Thus, producing an anode of better quality.
A third object of the present invention is providing an anode which is designed to be completely submerged below the electrolyte.
A fourth objet is providing a design of an anode which by itself operates the pivotable lugs so these can pass from the open position to a closed position.
A fifth object of this invention is providing a mounting method for an anode on a hanging means with pivotable lugs in such a way the anode is fixed on said hanging means so as it can secured and ready to be conveyed and introduced into an electrolytic cell.